Gao Zhiyong studied the difference of the cleavage bond between the scheelite and calcite crystal faces and its effect on the cleavage properties and surface properties of the mineral. Using Matthes Studio software to construct the unit cell of scheelite and calcite, calculate the main cleavage surface of different crystal faces of two calcium-bearing mineral crystals and the density of Ca active sites and the unsaturated bond density of active sites on the exposed surface, and calculate The results analyzed the cleavage properties and surface properties of the two minerals: the common cleavage planes of scheelite crystals are (001) plane, (101) plane and (111) plane; the common cleavage plane of calcite is crystal (1014) The common exposed surface is (2134) surface and (0118) surface; the order of unsaturated bond density of Ca active particles on different surfaces of crystal is: scheelite (101) ≥ (111) ≥ (001), calcite (2134) ) ≥ (0118) ≥ (1014). The Ca-mass nature of the mineral surface may be the key factor for the selective separation of the two calcium-containing minerals. Therefore, in the actual ore flotation, the hydrophobic surface can be increased by grinding or the like, and the hydrophilicity is reduced. The crystal face enhances the adsorption of the collector by the tungsten mineral and promotes the flotation of the mineral.
By the ocean wolframite, scheelite, garnet, calcite mineral fluorite crystal structure and chemical bond parameters are calculated, the crystal structure was found minerals, M represents a metal ion, X representative of non-metallic ions, Mn + -Xn- There is good agreement between bond length, ionic bond percentage, Coulomb force, ionic bond polarity, and relative bond strength. The shorter the Mn+-Xn- bond length, the smaller the ionic bond percentage, the smaller the polarity of the bond, the larger the Coulomb force between ions, the greater the relative bonding strength, and the more difficult the Mn+-Xn- bond is to break. The order of strength of the divalent metal ion M2+-Xn- bond in the mineral crystal structure is: wolframite > scheelite > garnet > calcite > fluorite, compared with other calcium-containing minerals, Ca2+ and scheelite surface The combination is the strongest; because fluorite has the highest ionic content, it has the strongest interaction with highly polarized water molecules and the strongest surface hydrophilicity.
Yu Yang also analyzed the surface flotation process of scheelite from the aspects of surface Ca2+ ion exposure, surface ΣCa2+/ΣXn-relative content, Ca-X bond strength and surface unsaturated bond strength. The selective inhibition mechanism of different modifiers on other calcium-containing minerals. Using complexing agents hexametaphosphate sodium phosphate to adjust the selectivity of other calcium minerals that inhibition: If the calcium-containing mineral surface strength is weak Ca-X, with the mineral surface modifier easily Ca2 + complexation masking effect in the liquid phase Thereby reducing the active particles of the mineral surface and the collector. If the surface of the calcium-containing mineral has a high ΣCa2+/ΣXn-, the surface of the mineral is highly positive, and the residual bond strength of the surface of the mineral is high. Therefore, the macromolecular organic regulator carboxymethylcellulose can be selectively inhibited. Other calcium-containing minerals. In the research on the floatability of scheelite and calcium-bearing minerals, it is pointed out that the calcium-containing mineral with weak surface Ca-X has a surface Ca2+ which easily interacts with the complexing regulator to form a poorly floatable complex and covers the surface. To achieve the purpose of changing the surface chemical composition of other calcium-containing minerals, to achieve selective separation of scheelite from other calcium-containing minerals.
Based on the first-principles study of density functional theory, Zhang Ying found that the density of states of calcium atoms in scheelite, fluorite and calcite is very similar. The density of states near the Fermi level of scheelite and calcite is mainly The 2p orbital structure of oxygen, the valence band near the fluorite Fermi level is mainly composed of F2p orbital. Therefore, scheelite and calcite are more active in oxygen when participating in chemical reactions, while fluorite is more active in fluorine. Strong; the surface of scheelite and calcite has unsaturated calcium ions, and the chemical bond between fluorine and fluorine on the surface of fluorite is most likely to break, but the free energy of fluoride ion is smaller than that of surface calcium, which is easy to give priority. The hydration enters the solution, causing the surface to also produce valence-unsaturated calcium ions, which exhibit similar flotation performance during flotation.
Hu Y calculated the chemical bond failure density and surface energy of heterogeneous surface in six surfaces of scheelite by density functional theory (DTF). The calculation results show that the surface energy is proportional to the chemical bond destruction density of the mineral surface, and (112) and (001) are the main damaged and exposed surfaces, which is confirmed by X-ray diffraction. The heterogeneous adsorption reaction and wettability of these two surfaces in sodium oleate and DDA solutions were investigated by contact angle test, AFM and flotation tests. At a given sodium oleate concentration, the (112) and (001) dissociation surface contact angle values ​​decrease, with a decrease (112) > (110). The same phenomenon was observed in the DDA solution. AFM, surface adsorption energy and molecular simulation calculations explain the heterogeneous adsorption reaction of oleic acid molecules on the (112) and (001) dissociation surfaces.
Gang Zhao studied the effects of cyclohexyl hydroxamic acid (CHA) as a new collector on the flotation of scheelite by density functional theory (DFT) calculation, mineral flotation test, adsorption measurement and potentiodynamic measurement. Density functional theory (DFT) calculations show that the anionic and neutral molecules of cyclohexyl hydroxamate or benzyl hydroxamate exhibit stronger chemical activity, and the phenyl ring is in the benzyl hydroxamic acid molecule. The hexyl substitution significantly enhances the electron donating ability of the hydroxamic acid collector. In an alkaline solution, two oxygen atoms in the cyclohexyl hydroxamic acid or benzyl hydroxamate have more negative charges than the other atoms, and as a result become their reaction centers. Cyclohexyl hydroxamate exhibits higher atomic charge values, molecular orbital energies, larger dipole moments, and bonding energy to Ca2+ ions, so it is stronger than benzyl hydroxamic acid to scheelite. Capturing ability. In addition, flotation test results, adsorption measurements, and potentiodynamic measurements confirmed that cyclohexyl hydroxamic acid has a stronger ability to capture than carbamic acid, and the results were consistent.
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